It’s not just for decoration. You can use it as a legitimate pointing device. Nudging it will move the mouse cursor and tapping it with your fingernail is clicking.
It takes some getting used to but you can definitely use it for normal office tasks if you wanted to. That being said, I still personally prefer a mouse. But I have known some people who like using the nipple.
Look no further than the dissent to United States v. Wong Kim Ark (when the Supreme Court ruled that the passage you cited grants citizenship by birthright), written by Chief Justice Melville Fuller, the mastermind behind such legal opinions as:
Anyway, he wrote:
and
So in other words, he was willing to rule that the constitution is optional as long as you are using it against undesirable races in order to get his way.